Breathing apparatus

ABSTRACT

A mask frame, comprises a central conduit connection aperture and lateral arms having a 3-D curvature. The lateral arms extend: outwardly from a center of the frame, rearwardly, towards the patients ears, and upwardly, along a vector passing from below the nose to a point between the temple the top of the ear. The lateral arms “twist” along their length, such that a bottom margin of an end of each lateral arm is positioned further away from a notional vertical plane passing through the centre of the conduit connection aperture than a top margin. Also provided is an anti-rotation feature which limits or prevents rotation between straps of a headgear, and the mask frame. Further provided is a buckle for a closed loop headgear the buckle being formed with a plurality of openings and posts configured to form an angled headgear strap path through the buckle through which part of a headgear strap loop can pass. The buckle also comprises a friction loop opening through which a further of the headgear strap loop can pass, the angle of the angled path being such that the further part of the headgear strap loop frictionally engages the friction loop opening.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application claims priority from U.S. 62/077,071 filed 11 Jul. 2014and from U.S. 62/212,431 filed 31 Aug. 2015, the entire contents of bothof which applications are hereby incorporated by reference.

BACKGROUND Technical Field

The presently disclosed subject matter invention generally relates tointerfaces for providing a supply of pressurised gas to a recipient.

Description of the Related Art

Breathing gases can be delivered to users with a variety of differentmask styles and can be delivered for a variety of different purposes.For example, users can be ventilated using non-invasive ventilation(NIV). In addition, continuous positive airway pressure (CPAP) orvariable airway pressure can be delivered using masks to treat a medicaldisorder, such as obstructive sleep apnea (OSA), chronic obstructivepulmonary disease (COPD), or congestive heart failure (CHF).

These non-invasive ventilation and pressure support therapies generallyinvolve the placement of a user interface device, which is typically anasal or nasal/oral mask, on the face of a user. The flow of breathinggas can be delivered from the pressure/flow generating device to theairway of the user through the mask.

Typically, patient interface devices include a mask frame that supportsa sealing member. The sealing member contacts the facial surfaces of theuser, including regions surrounding the nose, including the nose and thenares. Because such masks are typically worn for an extended period oftime, a variety of concerns must be taken into consideration. Forexample, in providing CPAP to treat OSA, the user normally wears themask all night long while he or she sleeps. One concern in such asituation is that the mask should be as comfortable as possible. It isalso important that the mask provide a sufficient seal against a user'sface without significant discomfort.

BRIEF SUMMARY

According to a first aspect of the invention there is provided a maskframe for a patient mask for delivering breathing gases to a patient,the mask frame comprising:

a central region comprising a conduit connection aperture configured tobe connected to a breathing gas delivery conduit, a notional centralvertical plane extending through the centre of the conduit connectionaperture; and

first and second lateral arms each extending outwardly from the centralregion away from the central vertical plane;

each lateral arm having a length and terminating in a distal end remotefrom the central region, each lateral arm comprising a top and bottommargin; wherein each lateral arm twists along its length such that thebottom margin at the end of each lateral arm is positioned further awayfrom the notional central vertical plane than the top margin at the endof each lateral arm.

The lateral arms may extend:

laterally outwardly from the central region of the frame;

rearwardly, towards the patients ears; and

upwardly, so that the lateral arms are angled upwards such that theyextend along a direction extending from the ends of the lateral arms toan area between the user's temples and ears. The lateral arms may extendupwardly along a vector passing from below the nose to a point betweenthe temple at the top of the ear.

Each lateral arm may comprise a planar, generally oblong, strip or band,the end of each strip defining top and bottom corners at the top andbottom margins respectively, wherein the side arms twist along theirlength such that the bottom corner of the ends of the lateral arms arepositioned further away from the central region of the frame than thetop corners.

Each lateral arm may be tapered along its length, that is, the distancebetween the top and bottom margins reduces along at least part of thelength of each lateral arm.

The ends of the lateral arms may be positioned below a notionalhorizontal mid plane that passes through the centre of the elbowconnection aperture.

The end of each arm may comprise a headgear connector configured toconnect the frame to headgear. The headgear connector may comprise aloop and a post configured to provide a connection point for a hook of aheadgear clip attached to headgear.

In some embodiments, the headgear connector may comprise a rotationlimiting formation configured to limit relative rotation betweenheadgear connected to the headgear connector, and the mask frame. Therotation limiting formation may comprise an end stop against which theheadgear abuts after a predetermined amount of relative rotation betweenthe mask frame and headgear. The rotation limiting formation may beprovided on the post. The rotation limiting formation may comprise twospaced apart end stops, relative movement between the headgear and themask frame being limited by the distance between the two spaced apartend stops.

According to another aspect of the invention there is provided a maskassembly comprising the mask frame of the first aspect, and furthercomprising: headgear configured to be connected to the lateral arms ofthe mask frame; and a sealing cushion configured to be mounted on themask frame.

According to a further aspect of the invention there is provided a maskassembly comprising a mask frame and a headgear configured to beconnected to the mask frame, at least one of the mask frame and headgearcomprising a connector comprising a post, the other of the mask frameand headgear comprising a connector comprising a hook configured toreceive the post to connect the headgear to the mask frame such that thehook can rotate about the post towards and away from the mask frame, themask assembly further comprising at least one rotation limitingformation configured to limit the extent of relative rotation betweenthe hook and post.

The rotation limiting formation may comprise an end stop on one of themask frame and headgear against which the other of the mask frame andheadgear abuts after a predetermined amount of relative rotation betweenthe mask frame and headgear. Two end stops may be provided, one on themask frame, the other on the headgear, the end stops being configured toabut after a predetermined amount of relative rotation between the maskframe and headgear. One end stop may be provided on the hook, and theother end stop may be provided on the post.

At least one of the hook and post may comprise two spaced apart endstops, relative movement between the hook and post being limited by thedistance between the two spaced apart end stops. One of the end stopsmay comprise a protrusion projecting from one of the hook and post, theother of the hook and post comprising a groove or recess having opposedends, the opposed ends forming the two spaced part apart end stops, theprotrusion being received in the groove or recess when the headgear isconnected to the mask frame and being configured such that theprotrusion moves within the groove or recess, between the opposed ends.The groove or recess may be provided on the post, the protrusion beingprovided on the hook.

According to another aspect of the invention there is provided aheadgear connector assembly for connecting a headgear to a mask, theheadgear connector assembly comprising a first connector comprising apost, and a second connector comprising a hook configured to receive thepost to connect the first connector to the second connector such thatthe hook can rotate about the post, the headgear connector assemblyfurther comprising at least one rotation limiting formation configuredto limit the extent of relative rotation between the hook and post.

According to a further aspect of the invention there is provided a maskassembly comprising a mask frame and a headgear configured to beconnected to the mask frame, the mask frame comprising:

a central region comprising a conduit connection aperture configured tobe connected to a breathing gas delivery conduit, a notional centralvertical plane extending through the centre of the conduit connectionaperture; and

first and second lateral arms each extending outwardly from the centralregion;

each lateral arm having a length and terminating in a distal end remotefrom the central region, each arm comprising a top and bottom margin;wherein

each lateral arm twists along its length such that the bottom margin atthe end of each lateral arm is positioned further away from the notionalcentral vertical plane than the top margin at the end of each lateralarm;

the headgear comprising straps having headgear connectors configured tobe rotatably connected to the ends of the lateral arms;

the mask assembly further comprising at least one rotation limitingformation configured to limit the extent of relative rotation betweenthe mask frame and the headgear.

According to another aspect of the invention there is provided a bucklefor a closed loop headgear, the buckle comprising:

an inside face and an outside face extending between a bottom face and atop face;

an inside post, a central post, and an outside post, each post extendingbetween the top and bottom faces;

a friction loop opening positioned between the inside post and thecentral post and configured to receive part of a headgear strap loop;

a front opening formed at least on the inside face;

an outside opening formed at least on the outside face;

a headgear strap path extending between the front opening and theoutside opening between the outside post and the central post, the pathbeing configured to receive a return part of the headgear strap loop,

wherein the front opening and the outside opening are offset such thatthe headgear strap path is angled.

The buckle may further comprise a strap attachment surface located on aninside surface of the outside post along the headgear strap path, thestrap attachment surface being configured to be attached to a strap ofthe headgear.

The front opening may be formed adjacent the bottom face of the buckle,such that the front opening extends through both the bottom face and theinside face.

The outside opening may be formed a distance along the outside face soas to be spaced from the bottom face.

The friction loop opening may comprise top and bottom margins at leastone of which is configured to frictionally engage the headgear straploop by virtue of the angle of the return part of the headgear strapthrough the angled path.

According to a further aspect of the invention there is provided aclosed loop headgear, comprising:

a buckle according to the aspect of the invention above;

a rear headgear section;

at least one strap extending forward from the rear headgear section,wherein the at least one strap passes through the friction loop openingbetween the inside post and the central post.

The strap preferably continues, passing through a hook connector of theheadgear and doubles back to form the return part of the headgear,passing back through the angled headgear strap path.

The strap may include a grip strap end that extends through the bucklefrom the outside opening. The grip strap end may have a length longenough to grasp between a thumb and one or two fingers. A dimple may beprovided for additional grip at a distal end of the grip strap end.

The rear headgear section may comprise a bifurcated rear section.

According to a further aspect of the invention there is provided anelbow for connecting a breathing gas delivery conduit to a patient maskassembly, the elbow comprising:

a ball joint section and a bottom portion;

an elongate tube section connecting the ball joint section and thebottom portion; wherein

the elongate tube section is narrower than the bottom portion and alargest diameter of the ball joint section.

The elongate tube section may include a front section configured to faceaway from the user, in use, and a rear section configured to facetowards the user, in use, the front section being longer than the rearsection.

The elongate tube section may form a truncated top where the frontsection and rear section connect to the ball joint section.

The elongate tube section may form an elbow having an angle θ between alongitudinal axis of the elongate tube section, and a longitudinal axisof the ball joint section.

The front section of the elongate tube section may include a pluralityof bias flow holes configured to enable CO2 washout during use. Theplurality of bias flow holes may be arranged in columns along a lengthof the front section, and in one embodiment the plurality of bias flowholes is arranged in two arrays of two columns with a space between thetwo arrays. The columns within each section may be offset, such that thebias flow holes of each row are nested with respect to each other, thatis, the bias flow holes of one column are at least partially located inspaces between the bias flow holes of an adjacent column. One column mayhave a different number of bias flow holes from another column.

The elongate tube section may include side sections, each having anotch. The notches may be configured to receive a feature of a diffuserbody having corresponding geometry.

In other aspects of the invention there is provided:

A: An apparatus as shown and described.

B: A mask frame, comprising: side arms having a 3-D curvature. The sidearms may extend: outwardly from a center of the frame, rearwardly,towards the patients ears, and upwardly, along a vector passing frombelow the nose to a point between the temple the top of the ear. Theside arms may twist along their length, such that bottom corner of theends of the side arms are positioned further away from a central portionof the frame than the upper corners.

C: An elbow, comprising:

a ball section and a wide bottom portion;

an elongate tube section connecting the ball section and the wide bottomportion;

the elongate tube section is narrower than the wide bottom end and alargest diameter of the ball section. The elongate tube section mayinclude a long front section (facing away from the user and mask, inuse) and a short rear section (facing towards the user and mask frame,in use). The elongate tube section may form a truncated top where thelong front section and short rear section connect to the ball section.The elongate tube section generally forms an elbow having an angle θ.The long front section of the elongated tube section may include aplurality of bias holes for CO2 washout during use. The plurality ofbias holes may be arranged in columns along a length of the long frontsection. The plurality of bias holes may be arranged in two sections oftwo columns with a space between the two sections. The columns withineach section may be offset, such that the bias holes of each row arenested with respect to each other. The elongated tube section mayinclude side sections, each having a notch. The notches may beconfigured to receive a corresponding geometry of a diffuser body.

D: A buckle for a closed loop headgear, the buckle comprising:

a bottom side and a top side;

an inside post, a central post, and an outside post, each extendingbetween the top and bottom sides;

a friction loop opening between the inside post and the central post;

a path comprising a front opening and an outside opening between theoutside post and the central post,

wherein the front opening and the outside are offset, forming an angledpath. A strap attachment surface may be located on an inside of theoutside post.

E: A closed loop headgear, may be provided comprising a buckle accordingto aspect D above and further comprising:

at least one strap extending forward from a rear section passes throughthe buckle between the inside post and the central post. The strap maycontinue, passing through the hook connector and doubles back, passingback through the central post and outside post of the buckle. The strapmay include a grip strap end that extends through the buckle from theoutside opening. The grip strap end may have a length long enough tograsp between a thumb and one or two fingers. A dimple may be providedfor additional grip at a distal end of the grip strap end. The rearsection may be a bifurcated rear section.

Various features, aspects and advantages of the present invention can beimplemented in any of a variety of manners. For example, while severalembodiments will be described herein, sets or subsets of features fromany of the embodiments can be used with sets or subsets of features fromany of the other embodiments.

The term “comprising” is used in the specification and claims, means“consisting at least in part of”. When interpreting a statement in thisspecification and claims that includes “comprising”, features other thanthat or those prefaced by the term may also be present. Related termssuch as “comprise” and “comprises” are to be interpreted in the samemanner.

In this specification where reference has been made to patentspecifications, other external documents, or other sources ofinformation, this is generally for the purpose of providing a contextfor discussing the features of the invention. Unless specifically statedotherwise, reference to such external documents is not to be construedas an admission that such documents, or such sources of information, inany jurisdiction, are prior art, or form part of the common generalknowledge in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will be described with reference to the following drawings.

FIG. 1 is a top, front, and left side perspective view of a non-limitingexemplary embodiment of a nasal respiratory mask configured to provide aflow of pressurized breathing gases directly to a user's nares.

FIG. 1a is a front view of a flexible gas supply conduit, elbow assemblyand swivel assembly that can be used with the mask of FIG. 1.

FIG. 1b is a side view of the flexible gas supply conduit, elbowassembly and swivel assembly of FIG. 1 a.

FIG. 1c is an enlarged perspective view of the elbow assembly and theflexible gas supply conduit of FIGS. 1a and 1 b.

FIG. 2a is a top, front, and left side perspective view of anon-limiting exemplary embodiment of a sealing cushion that can beincorporated into the mask of FIG. 1.

FIG. 2b is a bottom, rear, and right side perspective view of thesealing cushion of FIG. 2 a.

FIG. 3a is a top, front, and left side perspective view of anon-limiting exemplary embodiment of a mask frame comprising a proximalside, a distal side, a central region, and a lateral arm that extendsfrom each side of the central region and which can be incorporated withthe sealing cushion of FIGS. 2a and 2b into the mask of FIG. 1.

FIG. 3b is a bottom, rear, and right side perspective view of the maskframe of FIG. 3 a.

FIG. 4 shows an orthogonal front view of the mask frame of FIGS. 3a -3b.

FIG. 5 shows a corresponding orthogonal top view of the mask frame ofFIGS. 3a -3 b.

FIG. 6 shows a corresponding orthogonal side view of the mask frame ofFIGS. 3a -3 b.

FIG. 7 is a side view of a respiratory mask in use on a user U.

FIGS. 8 and 8A-8F show a non-limiting exemplary embodiment of an elbowthat can be incorporated into the mask of FIG. 1, optionally with thesealing cushion of FIGS. 2a-2b and the mask frame of FIGS. 3a -3 b.

FIGS. 9A-D show a non-limiting exemplary embodiment of a diffuserconfigured to connect to the elbow of FIGS. 8 and 8A-8F.

FIGS. 10A-10E show the elbow of FIGS. 8 and 8A-8F and diffuser assembly,wherein the diffuser is connected to the elbow such that the bias holesare covered.

FIGS. 11A-11B show a non-limiting exemplary embodiment of a maskassembly with a closed loop headgear.

FIGS. 12A-12F show a non-limiting exemplary embodiment of a buckle foruse in a closed loop headgear.

FIGS. 13A-13B are external perspective views of the buckle and strapused in the closed loop headgear.

FIGS. 14A-14B the headgear strap passes through the buckle incross-section.

FIGS. 15A-15B show the closed loop headgear in sliding and frictionmodes.

FIGS. 16A-16F show a non-limiting exemplary embodiment of a headgearconnector assembly for connecting a headgear to a mask.

DETAILED DESCRIPTION

As used herein the term “retaining forces” refers to any force appliedby a headgear to retain a respiratory mask on a user's face.

FIG. 1 shows a non-limiting exemplary embodiment of a nasal respiratorymask 1 configured to provide a flow of pressurized breathing gasesdirectly to a user's nares. The respiratory mask 1 comprises a sealingcushion 3, mask frame 5, elbow assembly 7, flexible gas supply conduit9, swivel assembly 11, headgear 13 and a pair of headgear clips 15.

Elbow and Flexible Gas Supply Conduit

With reference to FIGS. 1a to 1c an elbow assembly is configured toconnect to an elbow connection aperture 77 of the mask frame 5 (seee.g., FIGS. 1 and 3 a). The elbow assembly 7 includes a ball jointsection 21 and a wide bottom portion 23. An elongate tube section 25connects the ball joint section 21 and the wide bottom portion 23. Inthis example, the elongate tube section 25 is narrower than the widebottom portion 23 and a largest diameter of the ball joint section 21.The elongated tube section 25 includes a long front section 27 (facingaway from the user and mask 1, in use) and a short rear section 29(facing towards the user and mask frame 5, in use). The elongated tubesection 25 forms a truncated top 31 where the long front section 27 andshort rear section 29 connect to the ball joint section 21. In thisconfiguration, the elongated tube section 25 generally forms an elbowhaving a bend along its length, such that a longitudinal axis of aconduit receiving section to the elbow assembly 7 is not aligned with alongitudinal axis of the ball joint section 21.

The long front section 27 of the elongated tube section 25 includes aplurality of bias flow holes 35 for CO2 washout during use. Theplurality of bias flow holes 35 is arranged in columns along a length ofthe long front section, the columns generally being aligned with thelongitudinal axis of the elongated tube section 25. In particular, inthis example, the plurality of bias flow holes 35 is arranged in threecentral longer columns and two lateral shorter columns with a spacebetween the two sections. Each long central column has twelve bias flowholes in this example, and each short lateral column has seven bias flowholes. The columns are arranged on a tapering, keyhole shaped region ofthe long front section 27.

The wide bottom portion 23 is a short tube section that isconcentrically offset from a conduit receiving section, such that anannular channel is formed between the two. The conduit receiving sectionis configured to receive the flexible gas supply conduit 9 on its outersurfaces. The annular channel is configured to receive and retain theend of the flexible gas supply conduit 9. The conduit receiving sectionincludes an external thread, which is configured to retain the flexiblegas supply conduit 9. The wide bottom portion 23 is configured to hidethe end of the flexible gas supply conduit 9.

The flexible gas supply conduit 9 is a flexible tube comprising anexternal helical bead 41 and a thin conduit wall 43, supported by thebead 41. The bead 41 may contain an electrically conducting wire orstrip for providing heating to the conduit 9, or for transferring dataor sensor signals along the conduit 9. The thin wall 43 comprises aradially outwardly directed fold or bend 45 between each adjacenthelical coil. This outwardly directed fold 45 does not project outwardlyas far as the bead 41, such that the fold diameter is less than the beaddiameter, when the conduit 9 is in a neutral condition, as shown inFIGS. 1a to 1c . The bead 41, and fold 45, are configured such that theconduit 9 is flexible such that it can bend and can extend or contractlongitudinally. The fold 45 allows the conduit 9 to bend such that theconduit 9 is not straight in use. The fold 45 also allows the length ofthe conduit 9 to be varied. The bead 41 may be configured as a springsuch that any flexing, extending or contracting of the conduit 9 iselastic, with the bead 41 and/or the fold, returning the conduit 9 toits neutral condition, in the absence of force applied the to the endsof the conduit 9.

Sealing Cushion

The sealing cushion 3 is configured to engage with and form asubstantially airtight seal with the nares and outwardly facing surfacesof a user's nose, such that pressurized breathable gases are delivereddirectly to the nasal passage. Such a seal is described inPCT/NZ2014/000150 (publication number WO2015009172), filed 17 Jul. 2014,the entire contents of which are hereby incorporated by reference.

The sealing cushion 3 preferably comprises a seal body 51 and a maskframe connector 53. The seal body 51 can be formed of a soft andflexible material such that a supple pocket or envelope, that defines aninner cavity, is provided. The seal body 51 can be made of anyappropriate material such as, but not limited to latex, vinyl, siliconeor polyurethane.

Referring to FIGS. 2a and 2b the seal body 51 comprises a centralportion 55 and first and second lateral portions 57 extending from eachside of the central portion 55. The seal body 51 further comprises aninternal side 59 (FIG. 2b ) and an external side 61 (FIG. 2a ). Theinternal side 59 is positioned proximal to the user's face in use and isconfigured to provide sealing, stabilizing and locating surfaces. Theexternal side 61 is positioned distal to the user's face, relative tothe internal side 59, in use, and is configured to provide structure tothe sealing cushion 3.

The internal side 59 of the central portion 55 is configured to extendacross a base of a user's nose and the internal side of each of thelateral portions 57 is configured to curve around and extend across alateral side of the nose. These lateral portions 57 can form a perimeterseal on outwardly facing surfaces or flanks of the nose. The lateralportions 57 are outwardly flared away from the user's nose at the lowercorners, such that they contact the user's cheeks without digging in.The contact between the lateral portions 57 and the user's cheeksprovides a location through which retaining forces can be applied by theheadgear 13 to the user's face, in order to stabilize the respiratorymask 1.

The internal side 59 has a thin wall thickness such that the seal body51 is supple and capable of conforming to the geometry of the user'snose. The external side 61 comprises a greater wall thickness than theinternal side 59, such that it provides structure and stability to themore supple internal side 59.

The internal side 59 of the central portion 55 further comprises a pairof prongs 62. The prongs 62 comprise air delivery openings 63 andlocating surfaces 65. The air delivery openings 63 are configured toallow a flow of pressurized breathable gases to pass from within theseal body 51 to the user's airways. The locating surfaces 65 areconfigured to provide means of locating and sealing the prongs 62 withinthe user's nares and positioning the sealing cushion 3 on the nose.

The mask frame connector 53 is located within the external side 61 ofthe central portion 55, and comprises a substantially rigid ring that ispermanently attached to the seal body 51, by any appropriate means. Themask frame connector 53 is configured to provide an inlet through whichpressurized breathable air is delivered into the seal body 51. The maskframe connector 53 is further configured to provide a substantiallyairtight connection between the sealing cushion 3 and the mask frame 5;wherein the mask frame 5 and the sealing cushion 3 can be repeatedlyassembled and disassembled. The connection between the mask frame 5 andthe mask frame connector 53 may be achieved by any appropriate meansincluding but not limited to snap-fit, friction fit, threaded or bayonetmechanisms.

Mask Frame

As shown in FIGS. 3a and 3b the mask frame 5 comprises a proximal side71 (FIG. 3b ), a distal side 73 (FIG. 3a ), a central region 75, andfirst and second lateral arms 97 that extend from each side of thecentral region 75. The lateral arms 97 each comprise generally oblongplanar strips or bands having elongate top and bottom margins extendingalong the length of each arm 97. The lateral arms 97 are thus relativelywide when viewed from the front, but relatively narrow when viewed fromabove. The proximal side 71 is configured to be adjacent to the sealingcushion 3 and proximal to the user's face in use. The distal side 73forms the external surface of the mask frame 5. The distal side 73 ofthe central region 75 comprises an elbow connection aperture 77 whichcan optionally be circular. The elbow connection aperture 77 isconfigured to receive the ball joint 21 of the elbow assembly 17. Aplanar surface 81 extends radially outwardly from the elbow connectionaperture 77.

The proximal side 71 of the central region 75 comprises an annular wall83 that projects in a rearward direction towards the sealing cushion 3,around the perimeter of the elbow connection aperture 77.

The annular wall 83 comprises an internal surface 85 and an externalsurface 87. The internal surface 85 comprises a concave sphericalsection, configured to form a ball joint socket. The ball joint socketis configured to connect to corresponding geometry on the elbow assembly17, namely the ball joint section 21. The external surface 87 comprisesone or more indentations 91 configured to be coupled to correspondinggeometry on the mask frame connector 53 of the sealing cushion 3, suchthat a connection between the mask frame 5 and the cushioning seal isachieved.

FIG. 4 shows an orthogonal front view of the mask frame 5. The view isperpendicular to a front plane 80 that is coincident with the planarsurface 81 (see e.g., FIG. 3a ). The mask frame 5 is symmetrical about acentral vertical plane ‘y’, which passed through a center of the elbowconnection aperture 77. The mask frame 5 further comprises a top edgemargin 93 and a bottom edge margin 95, both of which extend from onelateral arm 97 through the central region 75 to the other lateral arm97. The top edge margin 93 is positioned such that it is above thebottom edge margin 95 both in the view of FIG. 4 and in use. Within thecentral region 75, the top edge margin 93 is offset from andsubstantially follows the curvature of the elbow connection aperture 77.The top edge margin 93 tapers outwardly (horizontally away from thecentral vertical plane ‘y’) in a largely downward direction as ittransitions from the central region 75 to each of the lateral arms 97.The bottom edge margin 95 curves outwardly in a somewhat upwarddirection from the central vertical plane ‘y’ region. As it transitionsfrom the ends of the central region 75 towards the end of each of thelateral arms 97 it curves in a slightly downward direction.

The tapered transitions of the top edge margin 93 and the bottom edgemargin 95 form the lateral arms 97, which are substantially elongatetapered members extending outwardly from each side of the central region75. The lateral arms 97 comprise a loop 99 and a post 101 configured toprovide a connection point for the headgear clips (see e.g., FIG. 14A).The loop 99 is a rectangular aperture that extends through the lateralarms 97 perpendicular to the distal side. In alternative embodiments theaperture may have any appropriate shape. The post 101 is formed by theouter wall of the loop 99 and forms the outer ends of the lateral arms97, and is substantially cylindrical. The post 101 is angled in anupwards direction towards the central region 77. This is shown by thewidth w₁ of the bottom edge being wider than the width w₂ of the topedge.

The ends of the lateral arms 97 are positioned substantially below ahorizontal mid plane ‘x’ that is perpendicular to the front plane andvertical plane y and passes through the center of the elbow connectionaperture 77. Thus, the lateral arms 97 taper towards the bottom half ofthe mask frame 5.

FIG. 5 shows a corresponding orthogonal top view of the mask frame 5. Itshows that the lateral arms 97 also extend in a rearward direction(distal to proximal) from the planar surface 81.

FIG. 6 shows a corresponding orthogonal side view of the mask frame 5.It can be seen that the end of the bottom edge margin 95 is closer tothe front plane than the end of the top edge margin 93. This results inthe length of the post 101 forming an acute angle α with the frontplane.

FIG. 7 is a side view of the respiratory mask 1 in use on a user U. Itcan be seen that, in use, the front plane is at an angle when the user Uis upright. The angle of the posts 101 (noted above with reference toFIG. 6) is such that the retaining force F applied by the headgear 13 issubstantially perpendicular to the angle of the post 101. This minimizestorsional forces between the headgear 13 and the mask frame 5, and thusimproves the stability of the respiratory mask 1 on the user U. Thelateral arms 97 are angled upwards such they extend along a directionextending from the ends of the lateral arms 97 to an area between theuser's temples and ears.

In other words, the lateral or side arms 97 have a 3-D curvature. Inuse, the lateral arms 97 extend: outwardly from the center of the frame5, rearwardly, towards the patients ears, and upwardly, along a vectorpassing from below the nose to a point between the temple the top of theear. Additionally, the lateral arms 97 “twist” along their length, suchthat bottom corners of the ends of the lateral arms 97 are positionedfurther away from the central vertical plane than the top corners, forexample, as shown in FIG. 5.

The positioning of the lateral arms 97 on the lower half of the maskframe 5 provides improved stability of the respiratory mask on theuser's face. The retaining forces F applied by the headgear 13 to themask frame 5 and sealing cushion 3 are predominantly applied through thelateral portions of the sealing cushion 3. This results in the retainingforces being applied predominantly to the lower surfaces of the user'snose, their upper lip and cheeks. This provides a greater surface areaover which the forces can be spread and thus greater stability. Thespreading of the forces over a greater surface area may also minimizeany pressure points on the user's face, which may cause discomfort. Ifthe lateral arms 97 were located higher on the mask frame 5 the forcevector F would be predominantly applied to the tip of the user's nose,which may provide reduced stability to the respiratory mask 1. This mayalso cause discomfort to the user in the form of a pressure point on thetip of their nose.

The lower positioning of the lateral arms 97 provides the respiratorymask 1 with a more minimal appearance. Since the mask frame 5 issubstantially positioned below the nose, in use, it is less visible andthus less dominating on the user's face. The lower positioning of thelateral arms 97 in combination with the angle of the post 99 alsoresults in the headgear 13 passing over the user's cheek at a greaterdistance below the eyes. This is beneficial in that the headgear 13 isless likely to fall within the user's peripheral vision, making the mask1 less obtrusive and more comfortable to wear.

Elbow and Diffuser

Shown in FIGS. 8 and 8A-8F is an elbow 117 similar to the elbow 17described above, and configured to connect to the elbow connectionaperture 77 (see e.g., FIGS. 1 and 3 a). The elbow 117 includes a balljoint section 121 and a wide bottom portion 123. An elongate tubesection 125 connects the ball joint section 121 and the wide bottomportion 123. The elongate tube section 125 is narrower than the widebottom portion 123 and a largest diameter of the ball joint section 121.The elongated tube section 125 includes a long front section 127 (facingaway from the user and mask, in use) and a short rear section 129(facing towards the user and mask frame 5, in use). The elongated tubesection 125 forms a truncated top 131 where the long front section 127and short rear section 129 connect to the ball joint section 121. Inthis configuration, the elongate tube section 125 generally forms anelbow having an angle θ.

The long front section 127 of the elongate tube section 125 includes aplurality of bias flow holes 135 for CO2 washout during use. Theplurality of bias flow holes 135 is arranged in columns along a lengthof the long front section 127. In particular, as shown, the plurality ofbias flow holes 135 is arranged in two sections or areas of two columnswith a space between the two sections or areas of the elongate tubesection 125. The columns within each section or area are offset, suchthat the bias flow holes of each row are nested with respect to eachother, that is, the bias flow holes of one column are nested at leastpartially within the spaces between the bias flow holes of anothercolumn. The elongated tube section 125 further includes side sections137, each having a notch 139. The notches 139 are configured to receivea part of a diffuser body having corresponding geometry.

The wide bottom portion 123 is short tube section that is concentricallyoffset from a conduit receiving section 141, such that an annularchannel 143 is formed between the two. The conduit receiving section 141is configured to receive the flexible gas supply conduit 9 on its outersurfaces. The annular channel 143 is configured to receive and retainthe end of the flexible gas supply conduit 9. The conduit 9 receivingsection includes a retaining formation which may be a projection andwhich is in this example is a screw thread 145, which is configured toretain the flexible gas supply conduit 9. The wide bottom portion 123 isconfigured to hide the end of the flexible gas supply conduit 9. Thus,the end of the flexible conduit 9 is threaded onto the elbow 117 toretain the conduit 9 on the elbow 117.

Shown in FIGS. 9A-D is a diffuser 151 configured to connect to the elbow117, covering the bias flow holes 135 such that gas exhausted from thebias flow holes 135 passes through the diffuser 151. The diffuser 151comprises a diffuser body 153 and a region or regions of a diffusermaterial 155. The diffuser body 153 comprises a substantially rigidplastic component having two lateral sides 157 and a front region 159there between. The diffuser body 153 is configured to have a curvaturethat compliments the curvature of the elongate tube section 125 of theelbow 117, extending from one side section across the long front sectionto the other side section. The diffuser body 153 further comprises oneor more diffuser openings 161 and a pair of grip tabs 163. The diffuseropenings 161 are located in the front region 159 such that they overlapthe bias flow holes 135, in use. In this example embodiment of thepresent disclosure the diffuser openings 161 are separated by a grillmember 165.

The grip tabs 163 extend approximately perpendicularly from the edges ofeach of the lateral sides 157 of the diffuser body 153, and have asubstantially trapezoidal profile. They are configured to allow thediffuser 151 to be gripped between the thumb and index finger of a user,during removal of the diffuser 151 from the elbow 117.

The diffuser body 153 has an internal surface 167, which is configuredto be proximal to the elongate tube section 125 of the elbow 117, inuse. The internal surface 167 comprises a pair of engagement tabs 169.The engagement tabs 169 extend inwardly from each of the grip tabs 163,and are configured to engage with the notches 139 of the elbow 117, suchthat the diffuser 151 is retained on the elbow 117.

The regions of diffuser material 155 are configured to fill the diffuseropenings 161, providing a torturous path for exhaled air to passthrough. The diffuser material 155 can be any breathable or porousmaterial. In use, the diffuser material 155 is flush with the bias flowholes 135, thus ensuring that air venting out of the bias flow holes 135is diffused through the diffuser material 155.

FIGS. 10A-10D show the elbow 117 and diffuser 151, wherein the diffuser151 is connected to the elbow 117 such that the bias flow holes 135 arecovered. It can be seen that, due to the narrow elongate tube section125 of the elbow 117, the diffuser 151 may now be configured to have awidth that is substantially equal to the outer diameter of the widebottom section 123 of the elbow 117. Additionally, the elongate tubesection 125 of the elbow 117 allows for longer columns of bias flowholes 135, and thus allows the elbow 117, and therefore the elbow 117and diffuser 151 to be narrower. This affords the elbow 117 and diffuser151 assembly a smaller and less bulky appearance.

Headgear

As shown in FIGS. 1 and 7 the respiratory mask 1 is secured in place ona user's head by a headgear 13. The headgear 13 comprises a three partconstruction, wherein the three parts include a pair of side straps 171and a rear portion 173. The side straps 171 are configured to join tothe rear portion 173 at one end and be connected to a headgear clip 175at the other end. The side straps 171 can be joined to the rear portion173 by any suitable means including but not limited to ultrasonicwelding, radiofrequency welding, adhesive(s) or sewing. The end of theside strap 171 that connects to the headgear clip 175 comprises asecurement tab 177 for adjustment of the headgear size. The securementtab 177 comprises the hook element of a hook and loop connector such asbut not limited to Velcro™. The securement tab 177 is configured toattach to the outer surface of the side strap 171 in order to secure thelength of the side strap 171, and thus the size of the headgear 13. Therear portion 173 comprises a bifurcated component having an upper andlower strap 173 a, 173 b, configured to engage a user's head in theoccipital region. The headgear 13 can be made from any suitablenon-stretch or stretch material known in the art, including but notlimited to Neoprene, TPE, Breathoprene™ or knitted fabric, or anycombination of materials. In a preferred embodiment the rear portion 173and side straps 171 are made from a single material in contrastingcolours. In alternative embodiments the rear portion 173 can be madefrom a different material to the side straps 171. In a furtheralternative embodiment the rear portion 173 and side straps 171 can be asingle colour.

Closed Loop Headgear

FIGS. 11A-11B show perspective and top views, respectively, of anon-limiting exemplary embodiment of a mask assembly 1 with a closedloop headgear 13. The mask assembly 1 is attached to a bifurcatedheadgear 13. Forward straps 171 extend forward from a rear, bifurcatedsection 173. The forward straps 171 pass through a buckle 179 then passthrough a hook 101 which is attached to the mask assembly 1. Eachforward strap 171 is doubled back, passing through the buckle 179.

The headgear 13 shown in FIGS. 11A-11B is a closed loop headgear,meaning that the length of the headgear can be adjusted from minimumlength to a maximum length, but cannot be fully disassembled. A closedloop configuration may be desirable because the headgear 13 cannot bedisassembled, and thus cannot be re-assembled incorrectly. The headgear13 can be made from any suitable non-stretch or stretch material knownin the art, including but not limited to Neoprene, TPE, Breathoprene™ orknitted fabric.

FIGS. 12A-12F show a non-limiting exemplary embodiment of a buckle 179for use in a closed loop headgear 13, such as shown in FIGS. 11A-11B.FIGS. 12A-12B show and in an inside view and an outside view,respectively, of the buckle 179. As shown, the buckle 179 includes abottom face 181 and a top face 183. Extending between the top and bottomsides 181, 183 are an inside post 185, a central post 187, and anoutside post 189. Between the inside post 185 and the central post 187is a friction loop opening 191. Between the outside post 189 and thecentral post 187 is a path comprising a front opening 193 and an outsideopening 195. The front opening 193 and the outside opening 195 areoffset, forming an angled path. Additionally, there is a strapattachment surface 197 located on an inside of the outside post 189.

Shown in FIGS. 12C-12D are perspective cross-sections of the buckle 179,in particular to show internal features. On the central post 187 is acentral post shoulder 199 and a central post recess 201.

Shown in FIGS. 12E-12F are front and back views, respectively of thebuckle, in particular to show additional views of the above describedfeatures.

FIGS. 13A-13B are external perspective views of the buckle 179 and strap171 used in the closed loop headgear 13. As shown, the strap 171extending forward from the rear section 173 passes through the buckle179 between the inside post 185 and the central post 187. The strap 171continues, passing through the hook (see e.g., 11A) and doubles back,passing back through the central post 187 and outside post 189 of thebuckle 179. The strap 171 includes a grip strap end 205 that extendsthrough the buckle 179. The grip strap end 205 has a length long enoughto grasp between a thumb and one or two fingers. A dimple 207 isprovided for additional grip.

FIGS. 14A-B show a cross-section of the strap 171 passing through thebuckle 179, forming an adjustable closed loop 209. The strap 171 passesthrough the friction loop opening 191 formed between the inside post 185and the central post 187. The strap 171 passes back through the buckle179, through the angled path formed between the front opening 193 to theoutside opening 195.

As shown, the buckle 179 is relatively angled with respect to the strap171. As a result of the angle in which the strap 171 passes through thefriction loop opening 191, there is an interference corner 192 thatgenerates a friction force that restricts the strap 171 from slidingthough when under a tension. In particular, the plane of the strap 171where the strap 171 passes through the friction loop opening is inclinedrelative to the plane of the buckle 179 so that the strap 171 is neitherperpendicular nor parallel to the buckle 179.

The strap 171 is permanently attached to the buckle 179 at a strapattachment surface 211 located on an inside of the outside post 189 (seee.g., FIG. 12A). Because the strap 171 is permanently attached to thebuckle 179, the headgear 13 cannot be disassembled (i.e., the hooks onthe adjustable closed loop cannot be removed). The strap 171 may beattached to the strap attachment surface 211 by any suitable meansincluding but not limited to ultrasonic welding, radiofrequency welding,adhesive(s) or sewing.

FIGS. 15A-B show the closed loop headgear 13 in sliding and frictionmodes, respectively. In FIG. 15A a pull force 204 is applied to the gripstrap end 205. This pull force causes the buckle 179 to rotate 206 inthe direction of the pull force (counter clockwise as shown). The“rotated” buckle 179 is represented in FIG. 15A as a dashed rectangle.The buckle 179 rotates with the pull force because the strap 171 isattached to the buckle 179 at the strap attachment surface 211. As thebuckle 179 rotates, the buckle 179, in particular the friction loopopening 191 becomes more perpendicular with the strap 171 sliding 208through the opening 191. As a result, the interference at theinterference corner 192 (see e.g., FIG. 14B), and therefore frictionforce, is decreased. This allows the strap 171 to pass freely (or atleast with less resistance) through the friction loop opening 191, thusallowing for adjustment.

Alternatively, as shown in FIG. 15B, a tension force 210 is applied, forexample, when the mask assembly 1 is in use. The tension force 210causes the buckle 179 to rotate 202 in the direction of the tensionforce (clockwise as shown). As the buckle 179 rotates, the buckle, inparticular, the friction loop opening 191 becomes more angled withrespect to the strap 171 passing through the opening 191. The “rotated”buckle 179 is represented in FIG. 15B as a dashed rectangle. As aresult, the interference at the interference corner (see e.g., FIG. 14B)increases, and therefore the friction force between the friction loopopening 191 and the strap 171 passing through, increases.

Headgear Connector Assembly

With reference to FIGS. 16A-16F, headgear 13 be connected to the maskframe 5 using a hook and post type headgear connector assembly 221. Inone example, the mask frame 5 comprises a post 101 on each lateral arm97. Each headgear clip 15 comprises a hook 15 a configured to receive arespective post 101 of the mask frame 5, to connect the headgear 13 tothe mask frame 5.

In one embodiment, each headgear clip 15 is able to rotate freely aboutthe respective post 101 on the mask frame 5. The post 101 is orientatedgenerally vertically in normal use of the mask 1 and headgear 13, andthe side straps 171 therefore rotate laterally about a generallyvertical pivot axis. This can have the effect that prior to the mask 1and headgear 13 being placed on the head of the user, the side straps171 of the headgear 13 have pivoted around the posts 101 on the maskframe 5 to a position where part of the headgear 13 is adjacent the mask1 and therefore impedes the mask 1 being located on the face of theuser. The side straps 171 of the headgear 13 may therefore rotate aroundthe posts 101 of the mask frame 5 such that the side straps 171 impedethe internal side of the seal body 53. This can make the mask 1 andheadgear 13 difficult or inconvenient to put on.

It may be desirable to be able to prevent, limit or control the extentof relative rotational movement between the headgear 13 and the maskframe 5, and particularly, to limit the extent of rotation of the sidestraps 171 of the headgear 13 relative to the mask frame 5.

With further reference to FIGS. 16A-16F, in one embodiment, the post 101of the mask frame 5 and the hook 15 a of the headgear clip 15 eachcomprise a respective movement limiting formation. These formations arearranged to engage to prevent, or at least limit the extent of, relativerotational movement between the mask frame 5 and the headgear 13, andmore particularly, between the mask frame 5 and the side straps 171 ofthe headgear 13. The headgear connector assembly 221 between the mask 1and headgear 13 therefore performs a rotation limiting function, to helpprevent the side straps 171 of the headgear 13 rotating relative to themask frame 5 to a position where they impede the mask 1, andparticularly the internal side of the seal body 53.

In one embodiment each post 101 of the mask frame 5 comprises a recessedregion, of reduced diameter as compared to the remainder of the post101, which forms a groove or recess 225 extending partially around thepost 101, in a plane perpendicular to the axis of the post 101. Whenviewed from above, that is, along the axis of the post 101, the grooveor recess 225 extends around only a portion of the post 101, that is,the groove or recess 225 is part circumferential. The groove or recess225 may extend through about 180° for example. The groove or recess 225thus comprises two opposed ends 225 a, 225 b where the groove or recess225 meets the non-recessed part of the post 101. These ends 225 a, 225 bare movement limiting formations comprising end stops.

Each hook 15 a also comprises a movement limiting feature which in oneexample comprises a bump or protrusion 227 on the inside face of thehook 15 a which functions as an end stop, that is, on the part of thehook 15 a which receives the post 101 in use. When the post 101 isreceived in the hook 15 a, which may be using a snap-fit typeconnection, relative rotation may occur between the post 101 and hook 15a with the bump 227 of the hook 15 a moving within the groove or recess225. This allows the side straps 171 of the headgear 13 to pivot aboutthe post 101 of the mask frame 5 to a limited extent. When a side strap171 has rotated a predetermined distance relative to the mask frame 5,the bump 227 reaches one end of the groove or recess 225 and abuts agroove or recess end stop 225 a, 225 b, this abutment preventing furtherrelative rotation between the hook 15 a and post 101. The bump 227 canthus travel a predetermined distance along the groove or recess 225before further movement of the bump 227, and therefore rotation of theside strap 171 relative to the mask frame 5, is prevented.

It will be appreciated that in another embodiment, the hook 15 a andpost 101 could be reversed, with the hook 15 a being provided on themask frame 5 and the post 101 being provided on the headgear clip 15.Likewise, it is envisaged that the bump or protrusion 227 could beformed on the post 101, and the groove or recess 225 on the hook 15 a.

The groove or recess 225 may be provided at any location along thelength of the post 101, that is, at any axial position on the post 101.More than one groove or recess 225 and bump 227 may be provided. Thelength of the groove or recess 225 and/or the size of the bump 227 maybe selected to achieve the desired degree of relative rotation betweenthe post 101 and hook 15 a.

In at least one embodiment, the groove or recess 225 is positioned on aleft side post 101 at a first vertical spacing and the groove or recess227 is positioned on a right side at a second vertical spacing. In someembodiments the first and second vertical spacing are different. Thecorresponding left and right hooks 15 a include a protrusion 225, theprotrusion 225 being at the first vertical height and the secondvertical height such that the left and right hooks 15 a are connectableto one of the left side post 101 or the right side post 101.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise”, “comprising”, and thelike, are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense, that is to say, in the sense of“including, but not limited to”.

Reference to any prior art in this specification is not, and should notbe taken as, an acknowledgement or any form of suggestion that thatprior art forms part of the common general knowledge in the field ofendeavour in any country in the world.

The inventions disclosed herein may also be said broadly to consist inthe parts, elements and features referred to or indicated in thespecification of the application, individually or collectively, in anyor all combinations of two or more of said parts, elements or features.

Where, in the foregoing description reference has been made to integersor components having known equivalents thereof, those integers areherein incorporated as if individually set forth.

It should be noted that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications may be madewithout departing from the spirit and scope of the inventions andwithout diminishing its attendant advantages. For instance, variouscomponents may be repositioned as desired. It is therefore intended thatsuch changes and modifications be included within the scope of theinventions. Moreover, not all of the features, aspects and advantagesare necessarily required to practice the present inventions.Accordingly, the scope of at least some of the present inventions isintended to be defined only by the claims that follow.

What is claimed is:
 1. A mask frame for a patient mask for deliveringbreathing gases to a patient, the mask frame comprising: a centralregion comprising a conduit connection aperture configured to beconnected to a breathing gas delivery conduit, a notional centralvertical plane extending through the centre of the conduit connectionaperture; and first and second lateral arms each extending outwardlyfrom the central region away from the central vertical plane; eachlateral arm having a length and terminating in a distal end remote fromthe central region, each lateral arm comprising a top and bottom margin;wherein each lateral arm twists along its length such that the bottommargin at the end of each lateral arm is positioned further away fromthe notional central vertical plane than the top margin at the end ofeach lateral arm.
 2. The mask frame of claim 1, wherein the lateral armsextend: laterally outwardly from the central region of the frame;rearwardly, towards the patients ears; and upwardly, so that the lateralarms are angled upwards such that they extend along a directionextending from the ends of the lateral arms to an area between theuser's temples and ears.
 3. The mask frame of claim 2 wherein thelateral arms extend upwardly along a vector passing from below the noseto a point between the temple at the top of the ear.
 4. The mask frameof any one of claims 1 to 3 wherein each lateral arm comprises a planarstrip, the end of each strip defining top and bottom corners at the topand bottom margins respectively, wherein the side arms twist along theirlength such that the bottom corner of the ends of the lateral arms arepositioned further away from the central region of the frame than thetop corners.
 5. The mask frame of claim 4 wherein each lateral arm istapered along its length, that is, the distance between the top andbottom margins reduces along at least part of the length of each lateralarm.
 6. The mask frame of any one of the preceding claims wherein theends of the lateral arms are positioned below a notional horizontal midplane that passes through the centre of the elbow connection aperture.7. The mask frame of any one of the preceding claims wherein the end ofeach arm comprises a headgear connector configured to connect the frameto headgear.
 8. The mask frame of claim wherein the headgear connectorcomprise a loop and a post configured to provide a connection point fora hook of a headgear clip attached to headgear.
 9. The mask frame ofclaim 7 or claim 8 wherein the headgear connector comprises a rotationlimiting formation configured to limit relative rotation betweenheadgear connected to the headgear connector, and the mask frame. 10.The mask frame of claim 9 wherein the rotation limiting formationcomprises an end stop against which the headgear abuts after apredetermined amount of relative rotation between the mask frame andheadgear.
 11. A mask assembly comprising a mask frame and a headgearconfigured to be connected to the mask frame, at least one of the maskframe and headgear comprising a connector comprising a post, the otherof the mask frame and headgear comprising a connector comprising a hookconfigured to receive the post to connect the headgear to the mask framesuch that the hook can rotate about the post towards and away from themask frame, the mask assembly further comprising at least one rotationlimiting formation configured to limit the extent of relative rotationbetween the hook and post.
 12. The mask assembly of claim 11 wherein therotation limiting formation comprises an end stop on one of the maskframe and headgear against which the other of the mask frame andheadgear abuts after a predetermined amount of relative rotation betweenthe mask frame and headgear.
 13. The mask assembly of claim 12comprising two end stops, one on the mask frame, the other on theheadgear, the end stops being configured to abut after a predeterminedamount of relative rotation between the mask frame and headgear.
 14. Themask assembly of claim 13 wherein one end stop is provided on the hook,and the other end stop is provided on the post.
 15. The mask assembly ofclaim 14 wherein at least one of the hook and post comprises two spacedapart end stops, relative movement between the hook and post beinglimited by the distance between the two spaced apart end stops.
 16. Themask assembly of claim 14 wherein one of the end stops comprises aprotrusion projecting from one of the hook and post, the other of thehook and post comprising a groove or recess having opposed ends, theopposed ends forming the two spaced part apart end stops, the protrusionbeing received in the groove or recess when the headgear is connected tothe mask frame and being configured such that the protrusion moveswithin the groove or recess, between the opposed ends.
 17. The maskassembly of claim 14 wherein the groove or recess is provided on thepost, the protrusion being provided on the hook.